Data processing: measuring – calibrating – or testing – Measurement system – Measured signal processing
Patent
1996-11-18
1999-05-11
Barlow, John
Data processing: measuring, calibrating, or testing
Measurement system
Measured signal processing
702189, 702193, 364724011, 3647242, 360 51, 360 65, G06F17/10
Patent
active
059038578
ABSTRACT:
A method and apparatus for calibrating an analog equalizer in a sampled amplitude read channel is disclosed wherein the filter's frequency response is measured and calibrated directly. This is accomplished by injecting a known periodic signal into the analog filter and measuring a spectrum value at a predetermined frequency. The filter parameters are adjusted accordingly until the spectrum reaches a predetermined target value. In the preferred embodiment, the analog filter comprises at least one second order low pass filter (referred to as a biquad filter), and the filter's spectrum is adjusted relative to the well known parameters f.sub.o and Q. Specifically, the parameters f.sub.o and Q are optimized relative to a power measurement at predetermined harmonics of the input signal. In this manner, the present invention enables auto-calibration of the analog equalizer without reading any data from the disc. Furthermore, the calibration process can be executed during the storage system's normal operation without significantly degrading its overall performance.
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U.S. application No. 08/583,295, Armstrong et al., filed Jan. 8, 1996.
Anderson Kent D.
Behrens Richard T.
Bliss William G.
Dudley Trent O.
Tuttle Tyson
Barlow John
Cirrus Logic Inc.
Sheerin Howard H.
Shifrin Dan A.
Vo Hien
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